Glow with depth in Blender?
Why would there be a glow around bright objects?

If the air is clean and transparent the light travels right through it, with no scattering and there is no glow around light sources or bright objects.



If there are particles floating in the air, those would get lit by the light source, light gets scattered, hence the perceived glow (think of a foggy night or the smog on a city)

With glass is the same thing: Clean and high quality glass would produce a non significant halo/glow around bright objects, the light would pass through it with very little dispersion. A dirty, scratched or humid glass would show the bright parts of an image with blurred edges caused by dispersion on the surface or the thickness of the glass itself (think a fogged or dirty window, or even a low quality or scratched camera lens)

So how do you create a glow then?


Option 1

Using the compositor would give you the option of the dirty glass. You can expand the brightess of the bright pixels using a glow node on the rendered image.


Option 2

If you want an environment with suspended particles then you use volume scatter in your world.



Maybe a bit exaggerated but just to get the point across.